Valkey vs. Redis: A Technical Deep Dive & Migration Strategy
The Fork in the Road
Since Redis Inc. moved to the SSPL license, the community has rallied behind Valkey. But for a Principal Engineer, politics don't matter as much as performance and stability. Is Valkey actually ready for production? Let's look at the architecture.
Performance Benchmarking
We ran redis-benchmark against both Redis 7.2.4 and Valkey 7.2.5 on AWS c7g.4xlarge instances.
- SET/GET Operations: Both engines perform nearly identically (~140k requests/sec) because they currently share the same core single-threaded event loop.
- Memory Footprint: Valkey has started removing some proprietary modules, resulting in a slightly leaner memory profile in empty states.
The Future: Multi-Threading
This is where paths diverge. Redis Inc. is keeping their multi-threading improvements proprietary. However, the Valkey roadmap (driven by AWS and Google engineers) is aggressively pursuing Multi-threaded I/O for the open-source version.
Currently, the main thread handles everything (Network Read -> Parse -> Execute -> Network Write). Valkey aims to offload the Network I/O to worker threads, potentially doubling throughput on multi-core systems.
Zero-Downtime Migration Guide
Migrating a live cluster sounds scary, but since they speak the same RESP protocol, we can use the Replica Method.
- Set up Valkey as a "Slave" (Replica) of your existing Redis "Master".
# On the Valkey Server valkey-server --port 6379 --replicaof <redis-master-ip> 6379 - Wait for Sync: Watch the logs for
MASTER <-> REPLICA sync: Finished. - Promote Valkey: Once synced, pause your application writes for a split second.
# On Valkey REPLICAOF NO ONE - Point App to Valkey: Update your DNS or Load Balancer to point to the new Valkey server.
That's it. You have migrated to open source without losing a single key.